1-(3-Aminophenyl)-4-[[3-[[4-[[[1-(3-aminophenyl)-3-carboxy-4,5-dihydro-5-oxo-1H-pyrazol]-4-yl]azo]benzoyl]amino]phenyl]azo]-4,5-dihydro-5-oxo-1H-pyrazole-3-carboxylic acid disodium salt